This invention relates to catheter delivery systems, and more specifically to a tubular device with improved torque and flexure characteristics.
Catheters, catheter guidewires, and flexible delivery devices have been used for several years to reach and provide treatment at target locations within the human body. For example, occlusion devices that seal heart defects are delivered to the treatment site via catheter, and balloon angioplasty is performed via catheter. Many designs for catheters and guidewires exist. The most important features of a catheter, guidewire, or delivery device are flexibility (so that it can navigate the winding human vasculature), and torque (so a physician can exert force sufficient to steer the device.) Most catheters are made of flexible plastic tubing and come in a variety of lengths and diameters. Most guidewires consist of a metal outer tube comprised of a metal coil coupled with an inner wire.
In practice, physicians generally use a guidewire first to reach the desired location in the body. Upon insertion, the guidewire is tracked with either X-ray technology or ultrasound as the physician maneuvers it to the target location within the patient's body. A catheter can then be advanced over the guidewire after the guidewire has reached the treatment site. The guidewire may be left in place or removed while treatment is accomplished via the catheter.
When the physician navigates to the treatment site, the guidewire must have sufficient flexibility to accomplish the sharp and numerous turns in the body's vasculature. If, however, the guidewire is too flexible, the resistance caused by surface contact with the body's vasculature and the numerous sharp turns will cause the guidewire to buckle and the physician will be unable to reach the treatment site. If the guidewire is too stiff, it will not be able to withstand the demanding angles of the vasculature and likewise will not be able to reach the treatment site. Thus there is a need in the art for a delivery tool that possesses both flexibility and navigability.